Sand plum jelly is made by cooking the fruit until it is soft and then straining the juice. The juice is then boiled with sugar until it thickens into a jelly. Sand plum jelly is a popular spread for toast, biscuits, and pancakes. It can also be used to make pies, jams, and other desserts.
Instructions
In a large pot, combine the sand plums and water. Bring to a boil, then reduce heat and simmer until the plums are soft, about 30 minutes.
Strain the juice from the plums, discarding the pulp.
In a large saucepan, combine the juice and sugar. Bring to a boil, then reduce heat and simmer until the jelly reaches 220ºF on a candy thermometer, about 20 minutes.
Stir in the pectin and cook for 1 minute more.
Pour the jelly into hot, sterilized jars and seal. Let the jars cool on a wire rack. Store the jelly in a cool, dark place.
Notes
Sand plums are small, round fruits that grow on wild plum trees in North America. They are typically yellow or orange in color and have a tart, sour flavor. Sans plums are also known as the wild plums, prairie plums, or sand cherries.
Source
Food in the U.S.A.